Table 2.

Major drivers for the total abundance of ciliates and the dominant species (>1% of total mean abundance) assessed by RDA with forward selection of significant parameters (P _adj. < 0.05). The percentage of the amount explaining the variation in the composition of the ciliate community is indicated in brackets. Note that Mesodinium cf. acarus is present only in the glacial turbid Lake FAS 3 and that the samples only for which the depth profiles of ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) measurements were available (i.e. July and August 2011) were included in the analyses. See also Figure S2 with a PCA of the abiotic parameters included in these analyses

	Clear lake – FAS 4	Glacier‐fed turbid lake – FAS 3
All ciliates	Underwater solar irradiance (65% UV‐B**)†	Underwater solar irradiance (41% PAR*)
Balanion planctonicum	Underwater solar irradiance (67% UV‐B**)‡	No significant parameter
Askenasia cf. chlorelligera	Underwater solar irradiance (78% UV‐B**)	Potential predators (46% rotifers*)§
Urotricha cf. furcata	Potential predators (62% rotifers*)	No significant parameter
Mesodinium cf. acarus	–	Potential predators (78% zooplankton*)

P levels with Benjamini–Hochberg correction for false discovery rates during multiple testing: **<0.01, *<0.05.

Alternative factors: ^†Zooplankton abundance (58%, **). ^‡Zooplankton abundance (63%, **). ^§Phytoplankton abundance (46%, **).